Paper dyed with water soluble benzothi-azolylphenylazobarbituric acid dyestuffs

ABSTRACT

MONOAZO DYESTUFFS OF THE FORMULA   2-(4-((2(Z=),4,6-DI(O=)HEXAHYDROPYRIMIDIN-5-YL)-N=N-),Y,   Q-PHENYL),4-X,6-R2,R1-BENZOTHIAZOLE   WHEREIN R1, X AND Y ARE HYDROGEN, LOWER ALKOXY OR LOWER ALKYL; R2 AND Q ARE H OR SO3H WITH AT LEAST ONE BEING SO3H; AND Q IS OXYGEN, SULFUR, IMINO, OR LOWER ALKYL IMINO. THESE DYESTUFFS COLOR PAPER AND PAPER PULP IN ATTRACTIVE GREENISH YELLOW SHADES BUT HAVE LITTLE AFFINITY FOR COTTON, SAID PAPER DYEINGS BEING ALKALI- AND ACID-FAST AND DISCHARGED ON CONTACT WITH CONVENTIONAL BLEACHING AGENTS.

United States Patent O PAPER DYED WITH WATER SOLUBLE BENZOTHI- AZOLYLPHENYLAZOBARBITURIC ACID DYE- STUFFS Alvin Carl Litke, West Seneca, N.Y., assignmto Allied Chemical Corporation, New York, N.Y-

No Drawing. Original application Sept. 23, 1970, Ser. No. 74,848, now Patent No. 3,726,851. Divided and this application Feb. 15, 1973, Ser. No. 332,952

Int. Cl. D21h 1/46 U.S. Cl. 8-7 9 Claims ABSTRACT OF THE DISCLOSURE Monoazo dyestuffs of the formula wherein R X and Y are hydrogen, lower alkoxy or lower alkyl; R and Q are H or SO H with at least one being 'SO H; and Q is oxygen, sulfur, imino, or lower alkyl imino. These dyestuffs color paper and paper pulp in attractive greenish yellow shades but have little aflinity for cotton, said paper dyeings being alkaliand acid-fast and discharged on contact with conventional bleaching agents.

CO-NH CO-NH This is a division of application Ser. No. 74,848, filed Sept. 23, 1970, now Pat. No. 3,726,851.

BACKGROUND OF THE INVENTION This invention relates to novel water-soluble monoazo dyestuffs and more particularly to novel bright greenishyellow dyes for paper. It is especially concerned with novel monoazo paper dyes containing the 2-phenylbenzothiazole nucleus.

It is known (see U.S. Pat. 3,426,010) to prepare watersoluble monoazo paper dyestuffs containing the 2-phenylbeniothiazole nucleus by coupling a diazotized 2-(4- aminophenyl)benzothiazole sulfonic acid (such as, diazotized 2-(p-aminophenyl)-6-methyl-7-benzothiazolesulfonic acid) with a coupling component which contains an aliphatic amido group, that is --CH CONH-, as a member of a heterocyclic nucleus, for example 3-methyl- 5 pyrazolone. These prior art dyestuffs color paper in relatively weak dull yellow shades having unattractive reddish tones.

It is the principal object of the present invention to devise novel water-soluble monoazo dyestuffs containing the 2-phenylbenzothiazo1e nucleus.

It is another object of the invention to prepare novel dyestuffs which dye paper in bright greenish-yellow shades of excellent tinctorial strength.

These and other objects and advantages will be apparent from the following description of my invention.

SUMMARY OF THE INVENTION The above objects are attained and the aforementioned disadvantages of the prior art dyestuffs are overcome in novel dyestuffs of the invention corresponding to the formula s Y c 0NH /c N=N-CH c=z R CO-NH 3,788,802 Patented Jan. 29, 1974 DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS 'IH'EREO'F The present novel dyestuffs are prepared by diazotizing an amine of the formula (wherein X, R R Q and Y have the aforementioned meanings) and coupling the resultant diazonium salt in aqueous media with barbituric acid or a Z-substituted derivative thereof. Diazotization, coupling and recovery of the dyestutf are effected in conventional manner, for example by the techniques disclosed in aforementioned U.S. Pat. 3,426,010.

- Although the dyestuffs of the invention are prepared from amine reactants similar to those of U.S. Pat. 3,426,- 010 and from coupling components containing an aliphatic arnido group as a member of a heterocyclic nucleus, the present dyes surprisingly color paper and paper pulp in yellow shades of an attractive greenish tone. Unexpectedly, the dyes of the invention are brighter and tinctorially stronger than the aforementioned prior art paper dyes. It was also surprising to discover that the instant dyestuffs, albeit strongly substantive to paper and paper pulp, have little afiinity for cotton.

The amine reactant charged in preparing the present dyestuffs should contain in accordance with the foregoing structural formula one or two aromatic sulfonic acid substituents, that is, sulfonic acid radicals including the sodium, potassium or other alkali metal salts thereof or the ammonium salts thereof. Suitable amine reactants can be prepared according to procedures disclosed by M. Schubert, Ann. 558, 10 (1947) and the aforementioned U.S. Pat. 3,426,010. Representative aromatic aminosulfonic acids suitable for preparing the present dyestuffs include the following examples listed in free acid form in azo-couplings with barbituric acid.

Z-(p-aminophenyl)-6-methyl-7-benzothiazolesulfonic acid barbituric acid 2-(p-aminophenyl)-6-methyl-5-benzothiazolesulfonic acid barbituric acid 2,-(3-rnethyl-4-amino-5-sulfophenyl)-4,6-dimethyl-7-benzothiazolesulfonic acid barbituric acid 2-(3-ethoxy-4-amino-S-sulfophenyl)-4-ethoxy-6-methyl- 7-benzothiazolesulfonic acid barbituric acid 2- (3-methyl-4-aminophenyl -6-methyl-7-benzothiazolesulfonic acid barbituric acid 2- 3-methoxy-4-aminophenyl) -4-methoxy6-methyl- 7-benzothiazolesulfonic acid barbituric acid 2-(3-methoxy-4-aminophenyl)-6-ethoxy-7-benzothiazolesulfonic acidbarbituric acid 2-(3-methoxy-4-amino-5-sulfophenyl)-6-isopropoxy- 7-benzothiazolesulfonic acid barbituric acid 2-(p-aminophenyl)-7-benzothiazolesulfonic acidbarbituric acid 2- (p-aminophenyl)-6-t-butyl-7-benzothiazolesulfonic acid barbituric acid Mixtures of these and equivalent Z-(p-aminophenyl) benzothiazolesulfonic acids can be employed in this respect also.

Preferably I employ as amine reactant a Z-(p-aminophenyl)-6-lower alkyl 'benzothiazole containing a single sulfonic acid 'substituent, especially 2-(p-aminophenyl)6- methyl-S- or 7-benzothiazolesulfonic acid.

Coupling components contemplated in preparing the present novel dyestuffs are barbituric and derivatives thereof which contain a divalent substituent other than oxygen in the 2 position of the barbituric acid nucleus. Typical suitable coupling components include the following representative examples:

barbituric acid 2-thiobarbituric acid 2-i'minoba rbituric acid 2-methyliminobarbituric acid 2-n-propylimino-barbituric acid 2-isopropyliminobarbituric acid 2-n-butyliminobarbituric acid 2-t-butyliminobarbituric acid.

Barbituric acid is the preferred coupling component of my invention.

The present novel dyestuffs dye paper and paper pulp in aqueous media according to conventional dyeing techniques, that is in the presence or absence of paper size and alum. Conveniently the present dyes are charged to the dyebath as an alkali metal salt or as a mixture of such salts, e.g. a mixture of lithium and sodium salts. If desired a dyestuif of the invention can be charged to the dyebath in the form of an aqueous solution of its alkali metal salt.

The present dyestuffs dye paper and paper pulp in fast bright yellow shades characterized by an attractive greenish tone. Paper dyeings of the invention also possess the commercially desirable properties of being alkaliand acid-fast and being discharged on contact with conventional bleaching agents, such as aqueous alkali metal hypochlorite.

In the following examples which serve to illustrate my invention, parts, percentages and proportions are by weight unless otherwise indicated and temperatures are in degrees centigrade.

EXAMPLE 1 To an agitated mixture of 33.7 parts (0.1 mol) of the ammonium salt of dehydrothio-p-toluidine monosulfonic acid (essentially 2- (p-aminophenyl) 6-methyl 7 benzothiazole monosulfonic acid-see Colour Index, 2nd ed., vol. 3, p. 3050) and 300 parts water are charged about 8 parts 50 B. aqueous sodium hydroxide. After the addition of 7.2 parts (0.104 mol) sodium nitrite, the mass is agitated for 10 minutes at ambient temperature. After addition of parts Solka Floc (a flocculent purified wood cellulose filter aid, Brown Co.) the mixture is filtered. Over a period of about two hours, the resultant filtrate is charged to a mixture of 47.7 parts of aqueous 20 B. hydrochloric acid and 50 parts water. The resultant mixture is agitated for one hour at Over a period of about thirty minutes, a 50% by volume aliquot of the resultant diazotization mixture is charged to a mixture of 6.3 parts (0.0384 mol) of barbituric acid, 50 parts of water and 7 parts lithium hyr xide monohydrate. The coupling mass is agitated for about 16 hours at ambient temperature and filtered to collect product which is dried at -90 under a current of circulating air. There is thus obtained 23 parts of a mixture of the sodium and lithium salts of the dyestuff which in its free-acid form has the structural formula:

This product dyes paper in a bright greenish yellow shade.

The following example illustrates the dyeing of paper with dyestuffs of the invention.

EXAMPLE 2 To 250 parts by volume of an aqueous slurry containing 3 parts paper pulp (Puget Sound Bleached Sulfite pulp) is charged 2.5 parts by volume of a solution prepared by dissolving about 0.75 part of the dye of Example 1 in about 500 parts by volume of water. After the resultant aqueous mixture has been agitated for about 5 minutes, 4 parts by volume of a 3% aqueous slurry of a fortified rosin size (Pexol, Hercules Powder Co.) and 4 parts by volume of a 10% aqueous solution of alum (aluminum sulfate octadecahydrate) are charged. After being agitated for an additional 20 minutes, the mixture is filtered through a metal screen. The recovered sheet of dyed pulp is pressed between two layers of blotting paper to express any adherent dye liquor and dried at about The resultant paper sheet is dyed in an excellent fast bright yellow shade having an attractive greenish tone.

When the foregoing procedure is repeated metting the size and alum, there is also obtained an excellent greenish-yellow paper dyeing.

The color of the above-described dyed paper samples is unchanged on contact with aqueous acid or alkali but is readily discharged on treatment with 2% aqueous sodium hypochloride for 15 minutes at about 50.

The aforementioned paper dyeings are substantially greener, stronger and brighter than comparable paper dyeings of the dyestuff of Example 1 of US. Pat. 3,426,- 010 (which is also charged to the dyebath in the form of a lithium-sodium salt mixture).

I claim:

1. Paper dyed with a water-soluble monoazo dyestuif of the structural formula:

wherein R X and Y are selected from hydrogen, lower alkoxy and lower alkyl radicals, R and Q are selected from hydrogen and sulfonic acid radicals, at least one of R and Q being a sulfonic acid radical, Z is selected from oxygen, sulfur, imino and lower alkylimino radicals.

2. The paper of claim 1 wherein the dyestuif contains a single sulfonic acid substituent.

3. The paper of claim 1 wherein Z is oxygen.

4. The paper of claim 1 wherein R X and Y are hydrogen or lower alkyl radicals.

5. The paper as claimed in claim 4 wherein R is methyl and X and Y are hydrogen.

5 6. The paper as claimed in claim 5 wherein the dyestulf contains one sulfonic acid radical.

7. The paper as claimed in claim 6 wherein Z is oxygen.

8. The paper as claimed in claim 7 wherein the dye- 5 stuff in its free-acid form has the structural formula SI O|H s cm 9. The paper as claimed in claim 7 wherein the dye stuff in its free-acid form has the structural formula:

6 References Cited US. Cl. X.R. 8-41 R; 162-162 Disclaimer 3,788,802.A$vz'n Owl Lz'tke, West Seneca, N.Y. PAPER DYED WITH WATER SOLUBLE BENZOTHIAZOLYLPHENYLAZO BAR- BITURIG ACID DYESTUFFS. Patent dated J an. 29, 1974. Disclaimer filed May 31, 1977, by the assignee, E. I du Pont ale N emours and Company. Hereby enters this disclaimer to claim 8 of said patent.

[Oyficz'al Gazette July 12, 1.977.] 

